This is Steven Salzberg's blog on genomics, pseudoscience, medical breakthroughs, higher education, and other topics, including skepticism about unscientific medical practices. Here's where I can say what I really think about abuses and distortions of science, wherever I see them.

chimps more diverse than humans?

I heard on the news yesterday that a new study discovered that chimps are "more evolved" than humans. It's too bad that the public will get that message, because it is really misleading. What the study found, by studying the genomes of several chimp populations, is that chimps have slightly more genes that appear to be evolving rapidly in response to their environment (this is called "positive selection"). In other words, this one study - whose methods are somewhat inaccurate to begin with, and which can only look at the parts of the genome that encode proteins - found about 225 genes in chimps that are evolving rapidly versus about 150 or so in humans. No surprise there - humans went through a population "bottleneck" in our relatively recent past, long after we diverged from chimps. A bottleneck occurs when the population gets very small, or when only a small number of individuals end up passing on their genes (which has the same effect) to subsequent generations. Anyway, the method didn't even attempt to look at the "noncoding" DNA, which is about 99% of our genome - it only looked at exons. So the study seems to be mostly an attempt to grab a headline, not much more. But what the heck are we supposed to think a journalist means by "more evolved", anyway? I think the implication is that somehow they are superior to us, and in some ways they are - better at climbing trees, for example! - but this phrase is almost meaningless. Bacteria are "more evolved" too, if you think about it. The study appeared in the Proceedings of the National Academy of Sciences, which makes the text freely available - so at least it's open access.